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United States Patent |
6,177,852
|
Tada
,   et al.
|
January 23, 2001
|
Dielectric filter, dielectric duplexer, and transceiver
Abstract
The present invention provides a dielectric filter and a dielectric
duplexer, each including a plurality of dielectric resonators. The
dielectric filter and the dielectric duplexer each comprising: a
dielectric block having a first surface and a second end surface opposite
to each other; at least three resonator holes passing through the first
end surface to the second end surface of the dielectric block; inner
conductors disposed on the inner wall surfaces of the resonator holes; an
outer conductor disposed on the external surface of the dielectric block;
the outer conductor on the first end surface of the dielectric block being
separated into an inner part and a peripheral part by a nonconductive
portion; the inner part including the openings of at least three of the
resonator holes adjacent to each other; a peripheral part being arranged
around the inner part; and the inner part and the peripheral part being
connected by a microinductance-generating means.
Inventors:
|
Tada; Hitoshi (Ishikawa-ken, JP);
Kato; Hideyuki (Ishikawa-ken, JP)
|
Assignee:
|
Murata Manufacturing Co., Ltd. (JP)
|
Appl. No.:
|
314992 |
Filed:
|
May 20, 1999 |
Foreign Application Priority Data
| May 21, 1998[JP] | 10-139575 |
| Apr 15, 1999[JP] | 11-108331 |
Current U.S. Class: |
333/202; 333/134; 333/206; 333/207 |
Intern'l Class: |
H01P 001/20; H01P 005/12 |
Field of Search: |
333/202,206,207,134
|
References Cited
U.S. Patent Documents
4823098 | Apr., 1989 | De Muro et al. | 333/206.
|
4896124 | Jan., 1990 | Schwent | 333/206.
|
5065120 | Nov., 1991 | Munn | 333/207.
|
5602518 | Feb., 1997 | Clifford, Jr. et al. | 333/202.
|
5793267 | Aug., 1998 | Tada et al. | 333/202.
|
6087911 | Jul., 2000 | Tada et al. | 333/206.
|
Foreign Patent Documents |
195 26 583 | Feb., 1996 | DE.
| |
0899806 | Mar., 1999 | EP.
| |
837405 | Feb., 1996 | JP.
| |
Primary Examiner: Pascal; Robert
Assistant Examiner: Nguyen; Patricia T.
Attorney, Agent or Firm: Ostrolenk, Faber, Gerb & Soffen, LLP
Claims
What is claimed is:
1. A dielectric filter including a plurality of dielectric resonators, the
dielectric filter comprising:
a dielectric block having a first surface and a second end surface opposite
to each other;
at least three resonator holes passing through the first end surface to the
second end surface of the dielectric block;
inner conductors disposed on the inner wall surfaces of the resonator
holes;
an outer conductor disposed on the external surface of the dielectric
block;
the outer conductor on the first end surface of the dielectric block being
separated into an inner part and a peripheral part by a nonconductive
portion;
the inner part including the openings of at least three of the resonator
holes adjacent to each other;
a peripheral part being arranged around the inner part; and
the inner part and the peripheral part being connected by a
microinductance.
2. The dielectric filter according to claim 1, wherein the openings of the
resonator holes included in the inner part are disposed in a recess
provided on the first end surface of the dielectric block, and the
nonconductive portion is disposed on the inner wall surface of the recess.
3. The dielectric filter according to claim 1 or claim 2, wherein the
microinductance is a conductor pattern integrated with the outer
conductor.
4. The dielectric filter according to claim 1 or claim 2, wherein the
microinductance is a metallic lead wire.
5. The dielectric filter according to claim 1 or claim 2, wherein a
coupling-block ground hole is disposed between the resonator holes the
openings of which are included in the inner part.
6. A dielectric duplexer including a plurality of dielectric resonators
constituting a transmitting side and a receiving side, comprising:
a dielectric block having a first end surface and a second end surface
opposite to each other;
at least three resonator holes passing through the first end surface to the
second end surface of the dielectric block and constituting a transmitting
side and a receiving side;
inner conductors disposed on the inner wall surfaces of the resonator
holes;
an outer conductor disposed on the external surface of the dielectric
block;
the outer conductor on the first end surface of the dielectric block being
separated into an inner part and a peripheral part by a nonconductive
portion;
the inner part including the openings of at least three of the resonator
holes adjacent to each other;
a peripheral part being arranged around the inner part; and
the inner part and the peripheral part being connected by a
microinductance.
7. The dielectric duplexer according to claim 6, wherein the openings of
the resonator holes included in the inner part are disposed in a recess
provided on the first end surface of the dielectric block, and the
nonconductive portion is disposed on the inner wall surface of the recess.
8. The dielectric filter according to claim 6 or claim 7, wherein the
microinductance is a conductor pattern integrated with the outer
conductor.
9. The dielectric filter according to claim 6 or claim 7, wherein the
microinductance is a metallic lead wire.
10. The dielectric filter according to claim 6 or claim 7, wherein a
coupling-block ground hole is disposed between the resonator holes the
openings of which are included in the inner part.
11. The dielectric filter according to claim 3, wherein a coupling-block
ground hole is disposed between the resonator holes the openings of which
are included in the inner part.
12. The dielectric filter according to claim 4, wherein a coupling-block
ground hole is disposed between the resonator holes the openings of which
are included in the inner part.
13. The dielectric filter according to claim 8, wherein a coupling-block
ground hole is disposed between the resonator holes the openings of which
are included in the inner part.
14. The dielectric filter according to claim 9, wherein a coupling-block
ground hole is disposed between the resonator holes the openings of which
are included in the inner part.
15. A radio communication device, wherein said device comprises at least
one radio circuit selected from the group consisting of a transmitting
circuit and a receiving circuit, said radio circuit comprising a
dielectric filter including a plurality of dielectric resonators, the
dielectric filter comprising:
a dielectric block having a first end surface and a second end surface
opposite to each other;
at least three resonator holes passing through the first end surface to the
second end surface of the dielectric block;
inner conductors disposed on the inner wall surfaces of the resonator
holes;
an outer conductor disposed on the external surface of the dielectric
block;
the outer conductor on the first end surface of the dielectric block being
separated into an inner part and a peripheral part by a nonconductive
portion;
the inner part including the openings of at least three of the resonator
holes adjacent to each other;
a peripheral part being arranged around the inner part; and
the inner part and the peripheral part being connected by a
microinductance.
16. A radio communication device comprising:
a dielectric duplexer including a plurality of dielectric resonators
constituting a transmitting side and a receiving side, comprising:
a dielectric block having a first surface and a second end surface opposite
to each other;
at least three resonator holes passing through the first end surface to the
second end surface of the dielectric block and constituting a transmitting
side and a receiving side;
inner conductors disposed on the inner wall surfaces of the resonator
holes;
an outer conductor disposed on the external surface of the dielectric
block;
the outer conductor on the first end surface of the dielectric block being
separated into an inner part and a peripheral part by a nonconductive
portion;
the inner part including the openings of at least three of the resonator
holes adjacent to each other;
a peripheral part being arranged around the inner part; and
the inner part and the peripheral part being connected by a
microinductance;
a transmitting circuit connected to said transmitting side of said
duplexer; and
a receiving circuit connected to said receiving side of said duplexer.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric filter, a dielectric
duplexer, and a transceiver.
2. Description of the Related Art
Recently, a small, light in weight, and thin-type of radio communication
equipment such as a mobile phone have been rapidly popular. In addition to
this tendency, electronic components which are to be mounted on such a
type of radio communication equipment are required to have a small size
and a reduced height. Furthermore, a dielectric duplexer, which is an
antenna-shared unit for performing reception and transmission by a single
antenna, is required to be small-sized, lightweight, and lower in height.
Conventionally, a dielectric duplexer used as an antenna-shared unit in a
mobile phone or the like adopts a structure in which resonator holes of a
plurality of dielectric resonators are aligned in a straight line in a
single dielectric block. However, generally, both a filter on the
transmitting side and a filter on the receiving side, which are composed
of dielectric resonators formed on the dielectric block, are allowed to
block a pass band of the counter-side filter by band-pass filter
characteristics, so that it is difficult to obtain sufficient attenuation
in an attenuation band, as long as the number of the dielectric resonators
is not increased. Thus, the dielectric duplexer having a structure in
which the resonator holes are aligned in a straight line, needs to be
large overall.
As a result, it is considerable, for example, that the transmitting filter
may be formed by a band-block filter. When a single dielectric block is
used, a transmission-line conductor is disposed for coupling adjacent
resonators by setting a phase difference of .pi./2 (rad) between them. In
this case, since the transmission line is a microstrip line whose
half-face is dielectric and its other half-face is air, the electrical
length of the line is longer than the resonator length of the dielectric
resonator, so that the dimension of the aligning direction of the
resonators is very large.
In addition, for example, even though the transmitting filter is used as a
band-block filter in the case of an antenna-shared unit, when the
transmitting filter side is viewed from the side of the receiving filter,
in the pass band of the receiving filter, namely, in the block band of the
transmitting filter, impedance is substantially zero, so that receiving
signals from the antenna flow to the side of the transmitting filter. In
order to avoid such a situation, it is necessary to dispose a phase unit
having the electrical length of .pi./2 between the transmitting filter and
an antenna terminal so as to make the impedance in the block band of the
transmitting filter viewed from the side of the receiving filter infinite.
However, this arrangement increases the number of components in the radio
communication equipment, thereby leading to rising in cost.
In order to solve the above-mentioned problems in the conventional
dielectric duplexer, for example, a duplexer shown in FIGS. 9A to 9C is
presented. The duplexer comprises rectangular-parallelepiped formed
dielectric block 1, and with respect to it, various holes, and an
electrode film are formed. In other words, 2a, 2b, 2c, 5a, 5b, and 5c are
resonator holes on the side of the transmitting filter of the dielectric
duplexer; and 4a, 4b, 4c, and 4d are resonator holes on the side of the
receiving filter. Numeral reference 3 is an input-output coupling
resonator hole.
Each of the respective resonator holes 2a through 5c is a step hole whose
internal diameters of the upper half part and the lower half part in FIG.
9B mutually differ. In order not to make the figure complicated, resonator
holes 5b and 5c are not shown in FIG. 9B. In this figure, 12a, 12b, and
12c are inner conductors formed on the inner wall surfaces of the
resonator holes 2a, 2b, and 2c; 15a is an inner conductor formed on the
inner wall surface of the resonator hole 5a; 14a, 14b, 14c, and 14d are
inner conductors formed on the inner wall surfaces of the resonator holes
4a, 4b, 4c, and 4d; and 13 is an inner conductor formed on the inner wall
surface of the input-output coupling resonator hole 3.
In addition, in each of the inner conductors except for the inner
conductors 12a and 13, a nonconductive portion indicated by g is disposed
near the extremity of a step hole having a longer internal diameter so as
to use this part as a disconnection end. Holes 6a, 6b, and 6c shown in
FIG. 9A are ground holes, in which inner conductors are formed on the
entire inner peripheral surfaces of the straight holes with fixed internal
diameters. On the external surface of the dielectric block 1 are formed a
transmitting terminal Tx and an antenna terminal ANT, respectively
connecting to the inner conductors 12a and 13 of the resonator holes 2a
and 3; and a receiving terminal Rx is formed to make capacitance between
it and the inner conductor 14d of the resonator hole 4d. Furthermore, an
outer conductor 10 is formed on the substantially entire surface except
for these terminals Tx, Rx, and ANT.
Meanwhile, in the dielectric duplexer having the aforementioned structure,
as shown in FIGS. 9A to 9C, since the resonator holes 2a through 2c, 3, 5a
through 5c and the ground holes 6a through 6c of the dielectric resonators
comprising a filter on the transmitting side are aligned in a staggering
form in the dielectric block 1, the dimension w of the aligning direction
of the resonator holes 2a through 2c is reduced, whereas the height h is
increased when it is mounted on a print circuit board, or the like. In
addition, in the conventional dielectric duplexer, arrangement of the
resonator holes 2a through 2c and the ground holes 6a through 6c are
complicated, and also it is difficult to form and manufacture the
dielectric block 1.
Furthermore, in the dielectric duplexer shown in FIG. 9, only Q.sub.0
characteristics of approximately 2/3 is obtainable as compared with the
one having the same height as that in which the resonator holes are
aligned in a line in the dielectric block; and when the height h is
reduced, the characteristics are deteriorated.
SUMMARY OF THE INVENTION
To overcome the above described problems, the present invention provides a
dielectric filter, a dielectric duplexer, and a transceiver, which have a
lower height and good characteristics, and can be easily manufactured.
One preferred embodiment of the present invention provides a dielectric
filter or a dielectric duplexer including a plurality of dielectric
resonators, the dielectric filter comprising: a dielectric block having a
first surface and a second end surface opposite to each other; at least
three resonator holes passing through the first end surface to the second
end surface of the dielectric block; inner conductors disposed on the
inner wall surfaces of the resonator holes; an outer conductor disposed on
the external surface of the dielectric block; the outer conductor on the
first end surface of the dielectric block being separated into an inner
part and a peripheral part by a nonconductive portion; the inner part
including the openings of at least three of the resonator holes adjacent
to each other; a peripheral part being arranged around the inner part; and
the inner part and the peripheral part being connected by a
microinductance-generating means.
The microinductance-generating unit is, for example, a conductor pattern
integrated with the outer conductor, or a metallic lead wire.
In the dielectric filter and the dielectric duplexer having such a
structure, among the respective dielectric resonators formed by at least
three resonator holes surrounded by the nonconductive portion, the
dielectric resonator using the first end surface side as a short-circuit
end is grounded through the microinductance generating unit. This
arrangement permits mutual comb-line coupling between the dielectric
resonators using the first end surface side as a short-circuit end among
the three dielectric resonators. As a result, it is not necessary to
dispose mutually coupling dielectric resonators in a staggering form in
the dielectric block.
In the above described dielectric duplexer or dielectric duplexer, the
openings of the resonator holes included in the inner part may be disposed
in a recess provided on the first end surface of the dielectric block, and
the nonconductive portion may be disposed on the inner wall surface of the
recess.
Since the recess allows the nonconductive portion and the openings of the
resonator holes to be recessed from a first end surface of the dielectric
block, influence of the leaking electromagnetic field on the other
electronic components mounted on a circuit board can be suppressed.
Similarly, influence of the electromagnetic field leaking from the other
electronic components on the dielectric filter and the dielectric duplexer
can be also suppressed.
In the above described dielectric filter or dielectric duplexer, a
coupling-block ground hole may be disposed between the resonator holes
which the openings thereof are included in the inner part. Such a
coupling-block ground hole between the resonator holes surrounded by the
nonconductive portion permits the coupling-block ground hole to cut off
mutual electromagnetic coupling between the resonator holes disposed on
both sides of the coupling-block ground hole by the blocking action.
Further, a transceiver employed in the present invention includes at least
either one of the dielectric filter or the dielectirc duplexer having the
aforementioned characteristics, so that the device can be flexible in
reducing the height thereof.
Other features and advantages of the present invention will become apparent
from the following description of preferred embodiments of the invention
which refers to the accompanying drawings, wherein like reference numerals
indicate like elements to avoid duplicative description.
BRIEF DESCRIPTION OF DRAWINGS
FIGS. 1A, 1B to 1C show a structure of a first preferred embodiment of a
dielectric duplexer according to the present invention, in which FIG. 1A
is a back view; FIG. 1B is a plan view; and FIG. 1C is a front view.
FIG. 2 is an electric equivalent circuit diagram of the dielectric duplexer
shown in FIG. 1.
FIG. 3 is a transmitting-side filter characteristic view of the dielectric
duplexer shown in FIG. 1.
FIG. 4 is a receiving-side filter characteristic view of the dielectric
duplexer shown in FIG. 1.
FIG. 5 is an electric equivalent circuit diagram showing a second preferred
embodiment of the dielectric duplexer according to the present invention.
FIG. 6 is a partially cut-away perspective view showing a structure of a
third preferred embodiment of the dielectric duplexer according to the
present invention.
FIG. 7 is a front view showing a fourth preferred embodiment of the
dielectric duplexer according to the present invention.
FIG. 8 is a block diagram showing one preferred embodiment of a transceiver
according to the present invention.
FIGS. 9A, 9B and 9C show a structure of a conventional dielectric duplexer,
in which FIG. 9A is a back view; FIG. 9B is a plan view; and FIG. 9C is a
front view.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[First Preferred Embodiment, FIGS. 1A through 4]
A first preferred embodiment of the dielectric duplexer according to the
present invention is shown in FIGS. 1A, 1B and 1C. In the dielectric
duplexer 20, the transmitting side comprises two band-block filters, and
the receiving side comprises two band-pass filters and a trap. In a
dielectric block 21 of a rectangular parallelepiped form are formed
resonator holes 22a through 22d of the transmitting filter side, resonator
holes 23a through 23d of the receiving filter side, an input-output
coupling resonator hole 24, and a ground hole 25. The resonator holes 22a
through 22d, 23a through 23d, 24, and the ground hole 25 are aligned in a
straight line in the dielectric block 21; and this arrangement is
different from the dielectric duplexer shown in FIG. 9.
Each of the resonator holes 22a through 22d, 23a through 23d, 24, and the
ground hole 25, as shown in FIG. 1B, are step holes which pass through a
first surface 26 of the dielectric block 21 to an opposing second surface
27, and the respective step holes have internal diameters of different
lengths in the upper half part and the lower half part thereof. Inner
conductors 32a through 32d are formed on the inner wall surfaces of the
resonator holes 22a through 22d; and inner conductors 33a through 33d are
formed on the inner wall surfaces of the resonator holes 23a through 23d.
An inner conductor 34 is formed on the inner wall surface of the
input-output coupling resonator hole 24. The ground hole 25 is a straight
hole having an internal diameter of a fixed length; and an inner conductor
35 is formed on the entire inner peripheral surface thereof.
In each of the inner conductors except for the inner conductors 32b, 33c,
and 34, a nonconductive portion indicated by g is formed near the
extremity of a step hole with a longer internal diameter, and this part
(which is, in other words, the part electrically separated from an outer
conductor 36) is a disconnection end. Meanwhile, the part of the inner
conductor opposing the disconnection part, (which is, in other words, the
part electrically connected to the outer conductor 36), is a short-circuit
end. On the external surface of the dielectric block 21 are formed a
transmitting terminal Tx connected to the inner conductor 32b of the
resonator hole 22b, a receiving terminal Rx connected to the inner
conductor 33c of the resonator hole 23c, and an antenna terminal ANT
connected to the inner conductor 34 of the resonator hole 24; and
furthermore, the outer conductor 36 is formed on the substantially entire
surface except for the transmitting terminal Tx, the receiving terminal
Rx, and the antenna terminal ANT.
As shown in FIG. 1C, in the inner part 41 on a first end surface 26 of the
dielectric block 21, the outer conductor 36 is cut away in a letter-C form
to dispose a nonconductve portion 43 in such a manner that the resonator
holes 22c and 22d, the input-output coupling resonator hole 24, and the
ground hole 25 are surrounded. A conductor pattern 44 left near the center
of the nonconductive portion 43 is integrated with the outer conductor 36;
and it is a microinductance generating means for mutually connecting the
inner part 41 and the outer part 42 which are electrically separated by
the nonconductive portion 43.
In the dielectric duplexer 20 having the aforementioned structure, the
disconnection ends and the short-circuit ends of the inner conductor 33a
formed in the resonator hole 23a and the inner conductor 33b formed in the
resonator hole 23b are disposed in the mutually same direction so as to
produce a comb-line coupling between the inner conductors 33a and 33b,
whereas the disconnection ends and the short-circuit ends of the inner
conductor 33a formed in the resonator hole 23a and the inner conductor 34
formed in the input-output coupling resonator hole 24 are disposed in the
mutually reversed direction so as to produce an inter-digital coupling
between the inner conductors 33a and 33b, and similarly, so as to produce
an inter-digital coupling between the inner conductor 33b formed in the
resonator hole 23b and the inner conductor 33c formed in the resonator
hole 23c. This permits formation of two band-pass filters between the
antenna terminal ANT and the receiving terminal Rx. In addition, an
inter-digital coupling occurs between the inner conductor 33c formed in
the resonator hole 23c and the inner conductor 33d formed in the resonator
hole 23d. This permits formation of a trap on the receiving side.
Meanwhile, a comb-line coupling occurs between the inner conductor 32c
formed in the resonator hole 22c and the inner conductor 34 formed in the
input-output coupling resonator hole 24 by the nonconductive portion 43,
whereas an inter-digital coupling occurs between the inner conductor 32b
formed in the resonator hole 22b and the inner conductor 32c formed in the
resonator hole 22c. This permits formation of a wide-band band-block
filter between the transmitting terminal Tx and the antenna terminal ANT.
Furthermore, an inter-digital coupling occurs between the inner conductors
32a formed in the resonator hole 22a and 32b formed in the resonator hole
22b, and between the inner conductor 32c formed in the resonator hole 22c
and the inner conductor 32d formed in the resonator hole 22d. This permits
formation of two traps on the transmitting side.
FIG. 2 shows an electric equivalent circuit diagram of the dielectric
duplexer 20. In the dielectric block 21 are disposed dielectric resonators
R1 through R4 formed by the respective resonator holes 22a through 22d on
the transmitting filter side, a dielectric resonator R5 formed by the
input-output coupling resonator hole 24, and respective dielectric
resonators R6 through R9 formed by the resonator holes 23a through 23d on
the receiving filter side. Between the dielectric resonators R1 and R3 is
disposed the dielectric resonator R2 which is connected to the
transmitting terminal Tx; between the dielectric resonators R4 and R6 is
disposed the dielectric resonator R5 which is connected to the antenna
terminal ANT; and furthermore, between the dielectric resonators R7 and R9
is disposed the dielectric resonator R8 which is connected to the
receiving terminal Rx. The dielectric resonator R4 and the dielectric
resonator R5 connected to the antenna terminal ANT are electromagnetically
mutually shielded by the inner conductor 35 of the ground hole 25.
In the transmitting side, a wide-band band-block filter is formed by the
dielectric resonators R2, R3, and R5, and the trap formed by the
dielectric resonators R2 and R4 is combined with this to comprise two
band-block filters. The dielectric resonators R3 and R5 are grounded
through a microinductance L1 (see FIG. 2) formed of a conductor pattern 44
which is located near the center of the nonconductive portion 43 shown in
FIG. 1C. Namely, regarding the dielectric resonators R3 and R5, the part
on the side of a first end surface 26 is a short-circuit end. This allows
a comb-line coupling between the dielectric resonators R3 and R5.
Furthermore, modifications in the form and pattern of the conductor
pattern 44 permit changing of values of the microinductance, so that
electromagnetic coupling between the dielectric resonators R3 and R5 can
be easily adjusted.
In this arrangement, the dielectric duplexer 20 is different from the
conventional dielectric duplexer shown in FIG. 9, since it is not
necessary to dispose the resonator holes 22a through 22d, 23a through 23d,
and 24 in the dielectric block 21 in a staggering form. This allows the
mounting height h of the dielectric duplexer 20 to be significantly lower
than that of the conventional dielectric duplexer, so that the dielectric
block 21 can be easily manufactured.
Under the condition in which the mounting height h is equal,
characteristics of the dielectric duplexer 20 are improved more than those
of the dielectric duplexer shown in FIG. 9. The measured values of pass
characteristics S21 and reflection characteristics S1 of the transmitting
filter in the dielectric duplexer 20 are shown in FIG. 3; and the measured
values of pass characteristics S21 and reflection characteristics S11 of
the receiving filter in the dielectric duplexer 20 are shown in FIG. 4.
[Second Preferred Embodiment, FIG. 5]
The electric equivalent circuit of a second preferred embodiment of the
dielectric duplexer according to the present invention is shown in FIG. 5.
In a dielectric duplexer 30, the dielectric resonator R4 and the
dielectric resonator R2 which is connected to the transmitting terminal Tx
are grounded through a microinductance L2. In other words, the structure
is equivalent to that in which the nonconductive portion 43 is disposed on
a first end surface 26 of the dielectric duplexer 20 employed in the first
embodiment by cutting away the outer conductor 36 in a letter-C form so as
to surround the resonator holes 22b, 22c, 22d, and the ground hole 25
which is disposed between the resonator holes 22b and 22c, on the inner
part 41. The microinductance L2 is formed by the conductor pattern 44,
which is located near the center of the nonconductive portion 43. The
dielectric resonator R3 and the dielectric resonator R2 which is connected
to the transmitting terminal Tx are electrically shielded to each other by
the inner conductor 35 formed in the ground hole 25 formed therebetween.
In the dielectric duplexer 30, similar to the first embodiment, the
dielectric resonators R2 and R4 are grounded through the microinductance
L2 to produce a comb-line coupling, so that the mounting height h can be
significantly lower than that of the conventional art, and the
characteristics can be enhanced.
[Third Preferred Embodiment, FIG. 6]
A third preferred embodiment of the dielectric duplexer according to the
present invention is shown in FIG. 6. A dielectric duplexer 40 has such an
arrangement that, in the dielectric duplexer 20 of the first embodiment,
respective openings of the resonator holes 22c, 22d, and 24, and the
ground hole 25 are formed in a recess 51 on a first end surface 26 of the
dielectric block 21; and the outer conductor 36 is cut away on the inner
peripheral wall of the recess 51 so as to dispose the nonconductive
portion 43.
When such an arrangement is provided, since the openings of the resonator
holes 22c, 22d, and 24, and the ground hole 25 are recessed from the first
end surface 26 of the dielectric block 21, in addition to the effects
created by the dielectric duplexer 20 of the first embodiment, high
frequencies generated in the dielectric duplexer 40 are unlikely to leak
outside. Moreover, influence due to high frequencies from the outside on
the dielectric duplexer 40 can be reduced.
[Fourth Embodiment, FIG. 7]
A front view of a fourth preferred embodiment of the dielectric duplexer
according to the present invention is shown in FIG. 7. A dielectric
duplexer 50 has such an arrangement that the nonconductive portion 43 of
the dielectric duplexer 20 shown in FIG. 1 is formed in a ring-shape, in
which the inner part 41 and the outer part 42 are mutually connected
through a metallic lead wire 44a so as to use the metallic lead wire 44a
as a microinductance. Such an arrangement permits easy adjustment of
inductance-values of the microinductance by modifying the length and shape
of the metallic lead wire 44a.
[Fifth Preferred Embodiment: FIG. 8]
A fifth preferred embodiment shows an embodiment of a transceiver according
to the present invention, in which an example of a mobile phone is
illustrated.
FIG. 8 is an electric circuit block diagram of RF section of a mobile phone
120. In FIG. 8, reference numeral 122 denotes an antenna device; reference
numeral 123 denotes an antenna-shared filter (duplexer); reference numeral
131 denotes a transmitting-side isolator; reference numeral 132 denotes a
transmitting-side amplifier; reference numeral 133 denotes a
transmitting-side inter-stage band-pass filter; reference numeral 134
denotes a transmitting-side mixer; reference numeral 135 denotes a
receiving-side amplifier; reference numeral 136 denotes a receiving-side
inter-stage band-pass filter; reference numeral 137 denotes a
receiving-side mixer; reference numeral 138 denotes a voltage-controlled
oscillator (VCO); and reference numeral 139 denotes a local band-pass
filter. In this case, it is possible to use, for example, the duplexer 20,
30, 40, or 50 of the first through fourth embodiments as an antenna-shared
filter (duplexer) 123. Mounting of the dielectric duplexer 20, 30, 40, or
50 can reduce the height of the RF section so as to obtain a slim mobile
phone. [Other Embodiments]
A dielectric filter, a dielectric duplexer, and a transceiver according to
the present invention should not be construed to the above-described
embodiments, and various changes and modifications are possible without
departing from the spirit and scope of the present invention. More
particularly, although a description has been given of a dielectric
dupulexer and a transceiver in the embodiments above, it is to be
understood that a dielectric filter such as a band-block filter or the
like can be applied.
As clearly seen from the given description above, according to the present
invention, since among respective dielectric resonators formed by at least
three resonator holes surrounded by a nonconductive portion, a dielectric
resonator, whose part of a first end surface side being a short-circuit
end, is grounded through a microinductance to produce a comb-line
coupling, it is not necessary to dispose the mutually coupling dielectric
resonators in a staggering form in a dielectric block, so that the
mounting height is significantly lower than that of the conventional art,
and the characteristics are also improved. Moreover, since the present
invention adopts a simple alignment of the resonator holes formed in the
dielectric block, manufacturing of the dielectric block is easy.
In addition, when at least three resonator holes surrounded by the
nonconductive portion are disposed in a recess formed on the short-circuit
surface of the dielectric block to form a nonconductive portion on the
inner wall surface of the recess, the short-circuit surfaces of the
dielectric resonators are recessed from a first end surface of the
dielecric block so as to strengthen shielding of the openings of the
dielectric resonators in the recess. This not only makes high frequencies
generated in the dielectric resonators unlikely to leak out, but also
permits influence due to high frequencies from the outside on the
dielectric resonators to be reduced. Furthermore, mounting a dielectric
filter and a dielectric duplexer according to the present invention allows
the height of a transceiver to be reduced.
While the invention has been particularly shown and described with
reference to preferred embodiments thereof, it will be understood by those
skilled in the art that the forgoing and other changes in form and details
may be made therein without departing from the spirit of the invention.
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